The present invention relates to a system for removing dirt, dust and the like from a flexible substrate, and more particularly to a system for the removal of ash and dust from perforated tipping paper used to wrap filter and tobacco components in the manufacture of cigarettes.
Over the years optical technology has been developed for the inspection of tipping paper used in the manufacture of cigarettes. Tipping paper may be cork-like or opaque white in appearance and is wrapped around a cigarette filter to join the filter to the end of a tobacco rod. Tipping paper is often perforated to impart a desired permeability to the paper to introduce air into tobacco smoke during the smoking process. Optical technology is often used to inspect the permeability of the paper during the perforation process before the paper is actually used in cigarette production. However, the optical devices used in this technology are quite sensitive to dust and dirt build-up as well as the ash remaining particularly when lasers are used to form the newly created holes. Overall, the perforation process generates significant quantities of dust and/or ash in addition to the dust and dirt already present on the tipping paper. Also, proper optical inspection requires that the paper path be stable and not oscillate from side-to-side.
Typical methods for cleaning the paper includes brushes, fixed guides or edges, air jets and/or general vacuum from fixed devices. These procedures provide some relief to dust build-up, but they do not effectively clean out the perforated holes which is necessary to ensure reliability of optical sensors to see through the perforations.
Another problem is that as the tipping paper moves along its path of travel the paper path is not stable. The paper tends to oscillate side-to-side which causes problems with alignment, sensing and rewind quality.